// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![allow(non_camel_case_types)]

//! Validates all used crates and extern libraries and loads their metadata

use back::svh::Svh;
use session::{config, Session};
use session::search_paths::PathKind;
use metadata::cstore;
use metadata::cstore::{CStore, CrateSource};
use metadata::decoder;
use metadata::loader;
use metadata::loader::CratePaths;
use plugin::load::PluginMetadata;
use util::nodemap::FnvHashMap;

use std::rc::Rc;
use std::collections::hash_map::Entry::{Occupied, Vacant};
use syntax::ast;
use syntax::abi;
use syntax::attr;
use syntax::attr::AttrMetaMethods;
use syntax::codemap::{Span};
use syntax::diagnostic::SpanHandler;
use syntax::parse::token::InternedString;
use syntax::parse::token;
use syntax::visit;
use util::fs;

struct Env<'a> {
    sess: &'a Session,
    next_crate_num: ast::CrateNum,
}

// Traverses an AST, reading all the information about use'd crates and extern
// libraries necessary for later resolving, typechecking, linking, etc.
pub fn read_crates(sess: &Session,
                   krate: &ast::Crate) {
    let mut e = Env {
        sess: sess,
        next_crate_num: sess.cstore.next_crate_num(),
    };
    visit_crate(&e, krate);
    visit::walk_crate(&mut e, krate);
    dump_crates(&sess.cstore);
    warn_if_multiple_versions(sess.diagnostic(), &sess.cstore);

    for &(ref name, kind) in sess.opts.libs.iter() {
        register_native_lib(sess, None, name.clone(), kind);
    }
}

impl<'a, 'v> visit::Visitor<'v> for Env<'a> {
    fn visit_view_item(&mut self, a: &ast::ViewItem) {
        visit_view_item(self, a);
        visit::walk_view_item(self, a);
    }
    fn visit_item(&mut self, a: &ast::Item) {
        visit_item(self, a);
        visit::walk_item(self, a);
    }
}

fn dump_crates(cstore: &CStore) {
    debug!("resolved crates:");
    cstore.iter_crate_data_origins(|_, data, opt_source| {
        debug!("  name: {}", data.name());
        debug!("  cnum: {}", data.cnum);
        debug!("  hash: {}", data.hash());
        opt_source.map(|cs| {
            let CrateSource { dylib, rlib, cnum: _ } = cs;
            dylib.map(|dl| debug!("  dylib: {}", dl.display()));
            rlib.map(|rl|  debug!("   rlib: {}", rl.display()));
        });
    })
}

fn warn_if_multiple_versions(diag: &SpanHandler, cstore: &CStore) {
    let mut map = FnvHashMap::new();
    cstore.iter_crate_data(|cnum, data| {
        match map.entry(data.name()) {
            Vacant(entry) => { entry.set(vec![cnum]); },
            Occupied(mut entry) => { entry.get_mut().push(cnum); },
        }
    });

    for (name, dupes) in map.into_iter() {
        if dupes.len() == 1 { continue }
        diag.handler().warn(
            format!("using multiple versions of crate `{}`", name)[]);
        for dupe in dupes.into_iter() {
            let data = cstore.get_crate_data(dupe);
            diag.span_note(data.span, "used here");
            loader::note_crate_name(diag, data.name()[]);
        }
    }
}

fn visit_crate(e: &Env, c: &ast::Crate) {
    for a in c.attrs.iter().filter(|m| m.name() == "link_args") {
        match a.value_str() {
            Some(ref linkarg) => e.sess.cstore.add_used_link_args(linkarg.get()),
            None => { /* fallthrough */ }
        }
    }
}

fn should_link(i: &ast::ViewItem) -> bool {
    i.attrs.iter().all(|attr| {
        attr.name().get() != "phase" ||
            attr.meta_item_list().map_or(false, |phases| {
                attr::contains_name(phases[], "link")
            })
    })
}

fn visit_view_item(e: &mut Env, i: &ast::ViewItem) {
    if !should_link(i) {
        return;
    }

    match extract_crate_info(e, i) {
        Some(info) => {
            let (cnum, _, _) = resolve_crate(e,
                                             &None,
                                             info.ident[],
                                             info.name[],
                                             None,
                                             i.span,
                                             PathKind::Crate);
            e.sess.cstore.add_extern_mod_stmt_cnum(info.id, cnum);
        }
        None => ()
    }
}

struct CrateInfo {
    ident: String,
    name: String,
    id: ast::NodeId,
    should_link: bool,
}

fn extract_crate_info(e: &Env, i: &ast::ViewItem) -> Option<CrateInfo> {
    match i.node {
        ast::ViewItemExternCrate(ident, ref path_opt, id) => {
            let ident = token::get_ident(ident);
            debug!("resolving extern crate stmt. ident: {} path_opt: {}",
                   ident, path_opt);
            let name = match *path_opt {
                Some((ref path_str, _)) => {
                    let name = path_str.get().to_string();
                    validate_crate_name(Some(e.sess), name[],
                                        Some(i.span));
                    name
                }
                None => ident.get().to_string(),
            };
            Some(CrateInfo {
                ident: ident.get().to_string(),
                name: name,
                id: id,
                should_link: should_link(i),
            })
        }
        _ => None
    }
}

pub fn validate_crate_name(sess: Option<&Session>, s: &str, sp: Option<Span>) {
    let err = |&: s: &str| {
        match (sp, sess) {
            (_, None) => panic!("{}", s),
            (Some(sp), Some(sess)) => sess.span_err(sp, s),
            (None, Some(sess)) => sess.err(s),
        }
    };
    if s.len() == 0 {
        err("crate name must not be empty");
    }
    for c in s.chars() {
        if c.is_alphanumeric() { continue }
        if c == '_' || c == '-' { continue }
        err(format!("invalid character `{}` in crate name: `{}`", c, s)[]);
    }
    match sess {
        Some(sess) => sess.abort_if_errors(),
        None => {}
    }
}

fn visit_item(e: &Env, i: &ast::Item) {
    match i.node {
        ast::ItemForeignMod(ref fm) => {
            if fm.abi == abi::Rust || fm.abi == abi::RustIntrinsic {
                return;
            }

            // First, add all of the custom link_args attributes
            let link_args = i.attrs.iter()
                .filter_map(|at| if at.name() == "link_args" {
                    Some(at)
                } else {
                    None
                })
                .collect::<Vec<&ast::Attribute>>();
            for m in link_args.iter() {
                match m.value_str() {
                    Some(linkarg) => e.sess.cstore.add_used_link_args(linkarg.get()),
                    None => { /* fallthrough */ }
                }
            }

            // Next, process all of the #[link(..)]-style arguments
            let link_args = i.attrs.iter()
                .filter_map(|at| if at.name() == "link" {
                    Some(at)
                } else {
                    None
                })
                .collect::<Vec<&ast::Attribute>>();
            for m in link_args.iter() {
                match m.meta_item_list() {
                    Some(items) => {
                        let kind = items.iter().find(|k| {
                            k.name() == "kind"
                        }).and_then(|a| a.value_str());
                        let kind = match kind {
                            Some(k) => {
                                if k == "static" {
                                    cstore::NativeStatic
                                } else if e.sess.target.target.options.is_like_osx
                                          && k == "framework" {
                                    cstore::NativeFramework
                                } else if k == "framework" {
                                    cstore::NativeFramework
                                } else if k == "dylib" {
                                    cstore::NativeUnknown
                                } else {
                                    e.sess.span_err(m.span,
                                        format!("unknown kind: `{}`",
                                                k)[]);
                                    cstore::NativeUnknown
                                }
                            }
                            None => cstore::NativeUnknown
                        };
                        let n = items.iter().find(|n| {
                            n.name() == "name"
                        }).and_then(|a| a.value_str());
                        let n = match n {
                            Some(n) => n,
                            None => {
                                e.sess.span_err(m.span,
                                    "#[link(...)] specified without \
                                     `name = \"foo\"`");
                                InternedString::new("foo")
                            }
                        };
                        register_native_lib(e.sess, Some(m.span),
                                            n.get().to_string(), kind);
                    }
                    None => {}
                }
            }
        }
        _ => { }
    }
}

fn register_native_lib(sess: &Session,
                       span: Option<Span>,
                       name: String,
                       kind: cstore::NativeLibraryKind) {
    if name.is_empty() {
        match span {
            Some(span) => {
                sess.span_err(span, "#[link(name = \"\")] given with \
                                     empty name");
            }
            None => {
                sess.err("empty library name given via `-l`");
            }
        }
        return
    }
    let is_osx = sess.target.target.options.is_like_osx;
    if kind == cstore::NativeFramework && !is_osx {
        let msg = "native frameworks are only available on OSX targets";
        match span {
            Some(span) => sess.span_err(span, msg),
            None => sess.err(msg),
        }
    }
    sess.cstore.add_used_library(name, kind);
}

fn existing_match(e: &Env, name: &str,
                  hash: Option<&Svh>) -> Option<ast::CrateNum> {
    let mut ret = None;
    e.sess.cstore.iter_crate_data(|cnum, data| {
        if data.name != name { return }

        match hash {
            Some(hash) if *hash == data.hash() => { ret = Some(cnum); return }
            Some(..) => return,
            None => {}
        }

        // When the hash is None we're dealing with a top-level dependency in
        // which case we may have a specification on the command line for this
        // library. Even though an upstream library may have loaded something of
        // the same name, we have to make sure it was loaded from the exact same
        // location as well.
        //
        // We're also sure to compare *paths*, not actual byte slices. The
        // `source` stores paths which are normalized which may be different
        // from the strings on the command line.
        let source = e.sess.cstore.get_used_crate_source(cnum).unwrap();
        match e.sess.opts.externs.get(name) {
            Some(locs) => {
                let found = locs.iter().any(|l| {
                    let l = fs::realpath(&Path::new(l[])).ok();
                    l == source.dylib || l == source.rlib
                });
                if found {
                    ret = Some(cnum);
                }
            }
            None => ret = Some(cnum),
        }
    });
    return ret;
}

fn register_crate<'a>(e: &mut Env,
                  root: &Option<CratePaths>,
                  ident: &str,
                  name: &str,
                  span: Span,
                  lib: loader::Library)
                        -> (ast::CrateNum, Rc<cstore::crate_metadata>,
                            cstore::CrateSource) {
    // Claim this crate number and cache it
    let cnum = e.next_crate_num;
    e.next_crate_num += 1;

    // Stash paths for top-most crate locally if necessary.
    let crate_paths = if root.is_none() {
        Some(CratePaths {
            ident: ident.to_string(),
            dylib: lib.dylib.clone(),
            rlib:  lib.rlib.clone(),
        })
    } else {
        None
    };
    // Maintain a reference to the top most crate.
    let root = if root.is_some() { root } else { &crate_paths };

    let cnum_map = resolve_crate_deps(e, root, lib.metadata.as_slice(), span);

    let loader::Library{ dylib, rlib, metadata } = lib;

    let cmeta = Rc::new( cstore::crate_metadata {
        name: name.to_string(),
        data: metadata,
        cnum_map: cnum_map,
        cnum: cnum,
        span: span,
    });

    let source = cstore::CrateSource {
        dylib: dylib,
        rlib: rlib,
        cnum: cnum,
    };

    e.sess.cstore.set_crate_data(cnum, cmeta.clone());
    e.sess.cstore.add_used_crate_source(source.clone());
    (cnum, cmeta, source)
}

fn resolve_crate(e: &mut Env,
                 root: &Option<CratePaths>,
                 ident: &str,
                 name: &str,
                 hash: Option<&Svh>,
                 span: Span,
                 kind: PathKind)
                     -> (ast::CrateNum, Rc<cstore::crate_metadata>,
                         cstore::CrateSource) {
    match existing_match(e, name, hash) {
        None => {
            let mut load_ctxt = loader::Context {
                sess: e.sess,
                span: span,
                ident: ident,
                crate_name: name,
                hash: hash.map(|a| &*a),
                filesearch: e.sess.target_filesearch(kind),
                triple: e.sess.opts.target_triple[],
                root: root,
                rejected_via_hash: vec!(),
                rejected_via_triple: vec!(),
                should_match_name: true,
            };
            let library = load_ctxt.load_library_crate();
            register_crate(e, root, ident, name, span, library)
        }
        Some(cnum) => (cnum,
                       e.sess.cstore.get_crate_data(cnum),
                       e.sess.cstore.get_used_crate_source(cnum).unwrap())
    }
}

// Go through the crate metadata and load any crates that it references
fn resolve_crate_deps(e: &mut Env,
                      root: &Option<CratePaths>,
                      cdata: &[u8], span : Span)
                   -> cstore::cnum_map {
    debug!("resolving deps of external crate");
    // The map from crate numbers in the crate we're resolving to local crate
    // numbers
    decoder::get_crate_deps(cdata).iter().map(|dep| {
        debug!("resolving dep crate {} hash: `{}`", dep.name, dep.hash);
        let (local_cnum, _, _) = resolve_crate(e, root,
                                               dep.name[],
                                               dep.name[],
                                               Some(&dep.hash),
                                               span,
                                               PathKind::Dependency);
        (dep.cnum, local_cnum)
    }).collect()
}

pub struct PluginMetadataReader<'a> {
    env: Env<'a>,
}

impl<'a> PluginMetadataReader<'a> {
    pub fn new(sess: &'a Session) -> PluginMetadataReader<'a> {
        PluginMetadataReader {
            env: Env {
                sess: sess,
                next_crate_num: sess.cstore.next_crate_num(),
            }
        }
    }

    pub fn read_plugin_metadata(&mut self,
                                krate: &ast::ViewItem) -> PluginMetadata {
        let info = extract_crate_info(&self.env, krate).unwrap();
        let target_triple = self.env.sess.opts.target_triple[];
        let is_cross = target_triple != config::host_triple();
        let mut should_link = info.should_link && !is_cross;
        let mut load_ctxt = loader::Context {
            sess: self.env.sess,
            span: krate.span,
            ident: info.ident[],
            crate_name: info.name[],
            hash: None,
            filesearch: self.env.sess.host_filesearch(PathKind::Crate),
            triple: config::host_triple(),
            root: &None,
            rejected_via_hash: vec!(),
            rejected_via_triple: vec!(),
            should_match_name: true,
        };
        let library = match load_ctxt.maybe_load_library_crate() {
            Some(l) => l,
            None if is_cross => {
                // try loading from target crates (only valid if there are
                // no syntax extensions)
                load_ctxt.triple = target_triple;
                load_ctxt.filesearch = self.env.sess.target_filesearch(PathKind::Crate);
                let lib = load_ctxt.load_library_crate();
                if decoder::get_plugin_registrar_fn(lib.metadata.as_slice()).is_some() {
                    let message = format!("crate `{}` contains a plugin_registrar fn but \
                                  only a version for triple `{}` could be found (need {})",
                                  info.ident, target_triple, config::host_triple());
                    self.env.sess.span_err(krate.span, message[]);
                    // need to abort now because the syntax expansion
                    // code will shortly attempt to load and execute
                    // code from the found library.
                    self.env.sess.abort_if_errors();
                }
                should_link = info.should_link;
                lib
            }
            None => { load_ctxt.report_load_errs(); unreachable!() },
        };
        let macros = decoder::get_exported_macros(library.metadata.as_slice());
        let registrar = decoder::get_plugin_registrar_fn(library.metadata.as_slice()).map(|id| {
            decoder::get_symbol(library.metadata.as_slice(), id)
        });
        if library.dylib.is_none() && registrar.is_some() {
            let message = format!("plugin crate `{}` only found in rlib format, \
                                   but must be available in dylib format",
                                  info.ident);
            self.env.sess.span_err(krate.span, message[]);
            // No need to abort because the loading code will just ignore this
            // empty dylib.
        }
        let pc = PluginMetadata {
            lib: library.dylib.clone(),
            macros: macros,
            registrar_symbol: registrar,
        };
        if should_link && existing_match(&self.env, info.name[],
                                         None).is_none() {
            // register crate now to avoid double-reading metadata
            register_crate(&mut self.env, &None, info.ident[],
                           info.name[], krate.span, library);
        }
        pc
    }
}